Karman has been busy with a GPS on-board computer for bicycle. In the beginning all he wanted was a speedometer but later it evolved in to feature packed cube of electronics. His nice clean design ended up with impressive parts list: 128×64 OLED display, Arduino Mini Pro, DC to DC converter, LiPo charger, savaged iPod-Nano battery, EM-411 GPS receiver and few discrete components like buttons, resistors and wires.
Everything is packed in to 6 layer cube of about inch size. It is able to display current course, altitude, speed, time, traveled distance, coordinates. Adding decent enclosure it should fit on to bicycle pretty well. Or simply drop in to pocket when hiking.